A wide range of equipment has been proposed to assist in the draining of fluid from wounds, particularly wounds resulting from surgery or accidents. One type of known construction employs a bellows type container that can be reduced in volume against the pressure of internal springs or by the force of deformation of the container material to provide a vacuum source.
These types of construction exhibit several major limitations one being that to achieve the desired level of vacuum, the container must have a high degree of resilience to develop a vacuum of the order of several pounds per square inch. This is somewhat impractical in terms of cost effective manufacture and it is not possible to effectively control or maintain the desired vacuum level for efficient drainage. Further, as only a small degree of vacuum can be created, it dissipates rapidly as the container fills with fluid. Also, it is normally very difficult, if not impossible, to monitor accurately the rate at which the fluid is collected.
Another known type of equipment for the extraction and collection of wound fluid employs a disposable container connected to a re-useable electronically driven pump, and thus require elaborate and expensive electronics, a pump and rechargeable batteries or a power supply. The inherent complexities of this type of device entails significant additional cost for initial purchase and for maintenance of the pump and controller. While the fluid containers are disposable, special provisions must be made to ensure that the non-disposable components, such as the pump assembly, are protected from contamination by the drained wound fluid.
Yet a further known type of wound fluid collector is that employing a pre-evacuated container which use volatile liquids such as pentane and hexane to achieve the required level of vacuum. However these do not provide a capability to vary or otherwise control the level of vacuum, and if a leak occurs which dissipates the vacuum there is no ability to re-establish the vacuum. These systems often operate at a higher degree of vacuum than is ideally desired for optimum drainage in many situations.
There is a variant of this latter form of wound fluid collector which use an elaborate, separate, non-adjustable regulator of the flexible throttled tube type which can be attached to the drain bottle. This does help to avoid an overly strong suction, but still has the other shortcomings of the non-regulated system and additionally there is the substantial added cost of the regulator, which cannot be re-used for another patient, as the regulator becomes contaminated by the drained wound fluids during use.